业务场景
我们知道在使用PageHelper分页插件时，会对执行PageHelper.startPage(pageNum, pageSize);方法后的第一条查询语句进行分页操作。在开发中总会遇到这样的业务情景，在进行分页查询后，需要对获得的列表数据包装成另一种类型，此时需要对新类型的列表进行分页，然而由于PageInfo<T>因为泛型的原因，导致处理后的列表不能加入到该类中。
如，我在数据库分页后查询到的类为PageInfo<User>，此时改类中的list属性为User，在当前的业务场景下，我需要将User类型替换为UserVo类型。
当我们对list属性进行操作时，会同时导致PageInfo类中的其他属性发生改变，如total等。
解决方法
//从数据库获得的Users分页列表 //当我们打印users时，会发现打印出来的数据除了列表数据还有分页属性 List<User> users = this.list(); //操作users获得的需要的列表 List<UserVo> userVos = this.list2(users); //创建User的info类，此时page中的属性已生成 PageInfo<User> userPage = new PageInfo<>(users); //创建UserVo的info类 PageInfo<UserVo> userVoPage= new PageInfo<>(userVos ); //将userPage中除看list外的其他属性复制到userVoPage中 PageInfoUtil pageInfoUtil = new PageInfoUtil(); pageInfo = pageInfoUtil.getPageVo(userPage ,userVoPage);
pageInfoUtil
public class PageInfoUtil {
public PageInfo getPageVo(PageInfo pageInfoPo,PageInfo pageInfoVo){
pageInfoVo.setTotal(pageInfoPo.getTotal());
pageInfoVo.setEndRow(pageInfoPo.getEndRow());
pageInfoVo.setHasNextPage(pageInfoPo.isHasNextPage());
pageInfoVo.setHasPreviousPage(pageInfoPo.isHasPreviousPage());
pageInfoVo.setIsFirstPage(pageInfoPo.isIsFirstPage());
pageInfoVo.setIsLastPage(pageInfoPo.isIsLastPage());
pageInfoVo.setNavigateFirstPage(pageInfoPo.getNavigateFirstPage());
pageInfoVo.setNavigateLastPage(pageInfoPo.getNavigateLastPage());
pageInfoVo.setNavigatePages(pageInfoPo.getNavigatePages());
pageInfoVo.setNavigatepageNums(pageInfoPo.getNavigatepageNums());
pageInfoVo.setNextPage(pageInfoPo.getNextPage());
pageInfoVo.setPageNum(pageInfoPo.getPageNum());
pageInfoVo.setPages(pageInfoPo.getPages());
pageInfoVo.setPageSize(pageInfoPo.getPageSize());
pageInfoVo.setPrePage(pageInfoPo.getPrePage());
pageInfoVo.setSize(pageInfoPo.getSize());
pageInfoVo.setStartRow(pageInfoPo.getStartRow());
pageInfoVo.setFirstPage(pageInfoPo.getFirstPage());
pageInfoVo.setLastPage(pageInfoPo.getLastPage());
return pageInfoVo;
}
}
End
想使用秀一点的方法，结果能力有限，没有成功，只能使用这种笨方法，如果有更好的方法，欢迎各位指导。
补充知识：mybatis-plus分页无效, total=0问题(springmvc)
前言
项目中(springmvc)分页采用mybatis-plus, 头一回用, 就遇到了如题问题
pom.xml
<dependency> <groupId>com.baomidou</groupId> <artifactId>mybatis-plus</artifactId> <version>3.2.0</version> </dependency>
mapper继承了BaseMapper
@Repository
public interface UserMapper extends BaseMapper<UserPo>{
// 这里代码没用, 查询采用的BaseMapper中的 IPage<T> selectPage(IPage<T> page, @Param("ew") Wrapper<T> queryWrapper);
}
service层
@Override
public SysUserVo list(UserQo qo) {
QueryWrapper<UserPo> queryWrapper = new QueryWrapper<>();
queryWrapper.like("name", qo.getKeyword())
.or().
like("code", qo.getKeyword());
Page<UserPo> page = new Page<>(qo.getPageNo(), qo.getPageSize());
IPage<UserPo> userPoIPage = userMapper.selectPage(page, queryWrapper);
List<UserPo> records = userPoIPage.getRecords();
long total = userPoIPage.getTotal();// 总记录数
long pages = userPoIPage.getPages();// 查询结果数
long pageNo = userPoIPage.getCurrent();// 当前页
long pageSize = userPoIPage.getSize();// 每页条数
List<UserVo> userVos = Lists.newArrayList();
for (UserPo userPo : records) {
Integer userId = userPo.getId();
List<RolePo> roles = userMapper.selectRoles(userId);
UserVo userVo = UserVo.builder().code(userPo.getCode())
.name(userPo.getName())
.rolePo(roles)
.status(userPo.getStatus())
.build();
userVos.add(userVo);
}
SysUserVo sysUserVo = SysUserVo.builder()
.list(userVos)
.total(total)
.build();
return sysUserVo;
}
结果分页并没有生效, 于是添加拦截器
package com.cebbank.api.config;
import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
import com.baomidou.mybatisplus.extension.plugins.pagination.optimize.JsqlParserCountOptimize;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.transaction.annotation.EnableTransactionManagement;
@Configuration
@EnableTransactionManagement
@MapperScan("com.cebbank.api.mapper")
public class MybatisPlusConfig {
@Bean
public PaginationInterceptor paginationInterceptor() {
PaginationInterceptor paginationInterceptor = new PaginationInterceptor();
// 设置请求的页面大于最大页后操作， true调回到首页，false 继续请求 默认false
paginationInterceptor.setOverflow(true);
// 设置最大单页限制数量，默认 500 条，-1 不受限制
paginationInterceptor.setLimit(100);
// 开启 count 的 join 优化,只针对部分 left join
paginationInterceptor.setCountSqlParser(new JsqlParserCountOptimize(true));
paginationInterceptor.setDialectType("mysql");
return paginationInterceptor;
}
}
还是没生效
最后找到解决方案, 在数据源配置中显式添加分页插件
@Bean
public SqlSessionFactory sqlSessionFactory() throws Exception {
MybatisSqlSessionFactoryBean sqlSessionFactoryBean = new MybatisSqlSessionFactoryBean();
sqlSessionFactoryBean.setDataSource(dataSource());
MybatisConfiguration configuration = new MybatisConfiguration();
configuration.setMapUnderscoreToCamelCase(true);
configuration.setDefaultEnumTypeHandler(EnumOrdinalTypeHandler.class);
sqlSessionFactoryBean.setConfiguration(configuration);
// sqlSessionFactoryBean.setMapperLocations(resolveMapperLocations());
sqlSessionFactoryBean.setPlugins(new Interceptor[]{new PaginationInterceptor()});
return sqlSessionFactoryBean.getObject();
}
完整配置
package com.cebbank.api.config;
import com.alibaba.druid.pool.DruidDataSource;
import com.baomidou.mybatisplus.core.MybatisConfiguration;
import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
import com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.type.EnumOrdinalTypeHandler;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.EnableAspectJAutoProxy;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import javax.sql.DataSource;
/**
* @author linyong
* @date 2020/7/30 16:38
* @description 数据源配置
**/
@Configuration
@EnableAspectJAutoProxy
@MapperScan("com.cebbank.api.mapper")
public class DBConfig {
@Value("${spring.datasource.url}")
private String url;
@Value("${spring.datasource.driver-class-name}")
private String driverClassName;
@Value("${spring.datasource.username}")
private String username;
@Value("${spring.datasource.password}")
private String password;
@Value("${spring.datasource.initialSize:5}")
private Integer initialSize;
@Value("${spring.datasource.maxActive:50}")
private Integer maxActive;
@Value("${spring.datasource.maxWait:60000}")
private Integer maxWait;
@Value("${spring.datasource.minIdle:5}")
private Integer minIdle;
@Value("${spring.datasource.testWhileIdle:true}")
private Boolean testWhileIdle;
@Value("${spring.datasource.testOnBorrow:true}")
private Boolean testOnBorrow;
@Value("${spring.datasource.testOnReturn:true}")
private Boolean testOnReturn;
@Value("${spring.datasource.validationQuery:select 1}")
private String validationQuery;
// @Value("${mybatis.mapper-locations}")
// private String mapperLocations;
@Bean
public DataSource dataSource(){
DruidDataSource druidDataSource = new DruidDataSource();
druidDataSource.setUrl(url);
druidDataSource.setDriverClassName(driverClassName);
druidDataSource.setUsername(username);
druidDataSource.setPassword(password);
druidDataSource.setInitialSize(initialSize);
druidDataSource.setMaxActive(maxActive);
druidDataSource.setMaxWait(maxWait);
druidDataSource.setMinIdle(minIdle);
druidDataSource.setTestWhileIdle(testWhileIdle);
druidDataSource.setTestOnBorrow(testOnBorrow);
druidDataSource.setTestOnReturn(testOnReturn);
druidDataSource.setValidationQuery(validationQuery);
return druidDataSource;
}
// private Resource[] resolveMapperLocations() {
// ResourcePatternResolver resourceResolver = new PathMatchingResourcePatternResolver();
// String[] arr = mapperLocations.split(",");
// List<String> locations = Arrays.asList(arr);
// List<Resource> resources = new ArrayList();
// if (locations != null) {
// for (String mapperLocation : locations) {
// try {
// Resource[] mappers = resourceResolver.getResources(mapperLocation);
// resources.addAll(Arrays.asList(mappers));
// } catch (IOException e) {
// // ignore
// }
// }
// }
// return resources.toArray(new Resource[resources.size()]);
// }
@Bean
public SqlSessionFactory sqlSessionFactory() throws Exception {
MybatisSqlSessionFactoryBean sqlSessionFactoryBean = new MybatisSqlSessionFactoryBean();
sqlSessionFactoryBean.setDataSource(dataSource());
MybatisConfiguration configuration = new MybatisConfiguration();
configuration.setMapUnderscoreToCamelCase(true);
configuration.setDefaultEnumTypeHandler(EnumOrdinalTypeHandler.class);
sqlSessionFactoryBean.setConfiguration(configuration);
// sqlSessionFactoryBean.setMapperLocations(resolveMapperLocations());
sqlSessionFactoryBean.setPlugins(new Interceptor[]{new PaginationInterceptor()});
return sqlSessionFactoryBean.getObject();
}
@Bean
public DataSourceTransactionManager transactionManager(){
DataSourceTransactionManager transactionManager = new DataSourceTransactionManager();
transactionManager.setDataSource(dataSource());
return transactionManager;
}
}
问题解决！
以上这篇解决Mybatis-Plus操作分页后数据失效问题就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持。
